Unitized ram drive for a punch press

ABSTRACT

A punch drive converts rotary motion from a power source in one embodiment into one-speed reciprocation or in another embodiment into selective two-speed reciprocation of a punch. In the latter embodiment the slower speed of reciprocation is provided by rolling a plurality of primary thrust balls between a rotating gear and a reciprocating primary wave thrust ring. The wave thrust ring has three cam waves which cause the thrust ring to be reciprocated downwardly as the balls roll thereover. The thrust ring is coupled through a clutch mechanism to the punch. The second speed is provided by a rotatable nibbling drive collar and a reciprocating nibbling wave thrust ring having a plurality of nibbling thrust balls therebetween. The nibbling wave thrust ring is provided with nine cam waves which cause reciprocation of the nibbling wave thrust ring as the thrust balls are rolled thereover. The nibbling wave thrust ring is also coupled to the punch. The rate of downward movement of the thrust rings is determined by the slope angles of the forward surfaces of the cam waves.

I United States Patent 1 [111 3,760,676

Daniels Sept. 25, 1973 UNITIZED RAM DRIVE FOR A PUNCH PRESS [57]ABSTRACT [75] Inventor: Dennis Daniels, Benevue, wash A punch driveconverts rotary motion from a power source in one embodiment intoone-speed reciproca- Asslgneel mada, Ltd., Seattle, a {ion or in anotherembodiment into selective two-speed {22] Filed: May 5 1972 reciprocationof a punch. In the latter embodiment the slower speed of reciprocationis provided by rolling a {21 PP NOJ 250,780 plurality of primary thrustballs between a rotating gear and a reciprocating primary wave thrustring. The wave 52 us. ca 83/590, 30/228, 74/57, thwst ring has Fhree CamWaves which cause the thrust 83/628 83/916 ring to be reclprocateddownwardly as the balls roll thereoven The thrust ring is coupledthrough a clutch [51] Int. Cl 823d 27/00 [58] Field of Search 83/590,628, 916; mechamsm h P T sewhd Speed 'h 30/228 372, 372 A; 74/56, 57 bya rotatable mbblmg drlve collar and a reciprocating I nibbling wavethrust ring having a plurality of nibbling [56] References Cited thrustballs therebetween. The nibbling wave thrust ring is provided with ninecam waves which cause re- UNITED STATES PATENTS ciprocation of thenibbling wave thrust ring as the l,367,827 2/1921 Noble 74/57 vthrustballs are rolled thereoven The nibbling wave g g 3; thrust ring is alsocoupled to the punch. The rate of W 3,403,668 10/1968 Schottler 74/56 xdownward movement of the thrust determmed Primary Examiner-J. M. MeisterAttorney-Richard W. Seed et al.

by the slope angles of the forward surfaces of the cam waves.

l2 Claims, 17 Drawing Figures STANDARD PUNCH UP POSITION PATENTEU3,760,675

I d SHEI 20f-6 NEUTRAL POSITION FIG. :3

l Tl l1 9 g V 68\ Q Q m i v 43 57,

46 I I 8 so NIBBLING DOWN POSITION PATENTE nsirzslsva 32760576 sum a a?6 STANDARD PUNCH POSITION a 13m 4 /6 5 v m NIBBLING POSITION IFJIGO 5FIRST, 6C FIG. 6A FIG. 6B

SHEEISQFS FIG, 11 0 A FIGO 11 0) 15% FHGO M) D FIGOHQQ UNITIZED RAMDRIVE FOR A PUNCH PRESS BACKGROUND OF THE INVENTION 1. Field of theInvention This invention relates to punch presses and more specificallyto drive mechanisms for'reciprocating the ram in a punch press.

2. Description of the Prior Art .Heretofore drives for punch presseshave relied on the use of a long drive shaft coupling a rotating flywheel with the punching mechanism. In punch presses using a deep throat,such as in C-type frame machines, the torque imposed on this long driveshaft causes bearing and twisting problems.

In prior art machines an air clutch is conventionally employed forengaging the punching mechanism with the continuously rotating flywheel. Such air clutches are generally undesirable because they arenoisy in operation and require a supply of high pressure air in thefactory.

Still another disadvantage of prior art drives for punch presses is thatconventionally the drive shaft is connected to the ram by an eccentricwhich does not provide its maximum downward force until the eccentric isat the bottom of its stroke. Since the punch begins to cut through theworkpiece prior to the eccentric being in the lowermost position, themaximum power of the punch is not realized until after the punch haspassed through the workpiece. Thus, the maximum power of the punch 'isnot utilized where it is most needed.

Still another disadvantage of prior art punch press drives is that theygenerally operate at only a single rate of reciprocation, whereas it isoften desirable to be able to provide for a rapid stroke with a lowerpower requirement, a slower stroke with more power, or even to providefor a period of dwell between the strokes.

SUMMARY OF THE INVENTION This invention pertains to a punch press drivehaving several unique features:

For example, it is an object of this invention to provide a unitized ramdrive located directly adjacent the flywheel of the power supply.

It is another object of this invention to provide a drive for a punchpress which converts the rotary motion of the power supply toreciprocation of the ram through the use of a plurality of thrust ballsrolling over cam waves on a reciprocal member.

It is another object of this invention to provide a ram drive for apunch press which is quiet in operation and more efficiently convertsrotary power to reciprocating movement.

This feature of the invention is obtained by a unitized drive locateddirectly adjacent the flywheel of the power supply. The drive convertsthe rotary motion of the power supply to linear reciprocation of the ramby the use of thrust balls rolling between two spaced members. One ofthese members has a plurality of cam waves which when the balls arerolled thereover causes the other member to reciprocate. The two membersare biased toward one another to maintain the engagement against thethrust balls and clutch means is provided to limit the movement towardsone another to allow the balls to be disengaged so that rotation of theone member may continue without reciprocating the other member.

It is another object of this invention to provide a ram drive for apunch press which readily provides for an infinite variety of linearspeeds for the downward stroke of the ram, or linear speeds for upwardstroke of the ram, or dwell between strokes.

It is an object of this invention to provide a drive for a punch presswhich allows selection of the maximum punching force to be provided atany location along the stroke of the ram.

This feature is obtained by adjusting the slope of the forward surfaceof the cam waves to provide any desired rate of movement during thedownward stroke of the ram at any location along the stroke so thatmaximum power can be obtained as the punch is initially contacting andcutting through the workpiece.

It is another object of this invention to provide a ram drive for apunch press which may be selectively shifted between a slow speedstandard punching operation to a high speed nibbling operation.

This feature is obtained by providing double sets of balls and thrustconverting members with the cam waves for one of the thrust convertingmembers being more plentiful than on the other so that by a simpleclutching mechanism, the rate of reciprocation can be alternated fromstandard or slow speed punching to nibbling or faster speed punching.Clutching in the preferred embodiment is obtained by the use of apowered shifiting mechanism remotely controlled by the operator of themachine.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a fragmentary verticalsection of a unitized ram drive embodying the principles of theinvention shown in a standard punch up position but with a nibblingpunch.

FIG. 2 is a schematic along a transverse section of the ram driveshowing the positions of the sections for each of the three operationalviews of FIGS. 1, 3 and 4.

FIG. 3 is a fragmentary vertical section taken along the line 3-3 ofFIG. 2 and illustrating the ram drive in a neutral position.

FIG. 4 is a fragmentary vertical section of the ram drive taken alongthe line 44 and illustrating the ram drive in a nibbling down position.

FIG. 5 is a fragmentary isometric of the unitized ram drive with partsbroken away for clarity.

FIGS. 6A-6C illustrate positions of the clutching mechanism in thenibbling, neutral, and standard punching positions, respectively, andillustrating the sequence of steps to engage the drive in the nibblingposition.

FIG. 7 is an exploded isometric of a portion of the unitized ram driveshown in FIG. 1.

FIG. 8 is a schematic illustration showing the relative movement betweenthe parts of the unitized ram drive and illustrating the slope changesfor varying the speed of the stroke of the ram.

FIG. 9 is a fragmentary horizontal section illustrating operations ofthe clutching mechanism.

FIGS. IOA-IOE are schematic illustrations showing the operationssequence for standar punching and for nibbling punching.

FIG. 1 1 is a fragmentary section illustrating a simplified preferredform of single speed ram drive embodying the principles fo theinvention.

DESCRIPTION OF THE PREFERRED EMBODIMENT The unitized ram drive of thisinvention is adapted to be used as a substitute for the drive with anyconventional punch press. In the preferred form of the embodiment anelectric motor or other power source, not shown, is coupled to aflywheel 12 by a plurality of conventional v-belts 13. The flywheel iskeyed to a flywheel drive shaft 14 that is rotatably mounted in a fixedrigid frame 15. As is well understood, the frame 15 is a part of theframe of the punch press and is sufficiently rigid to withstand thereaction force of the punch as it is driven through the workpiece W.Although not shown, it is understood that a suitable table is providedbelow the workpiece to hold a die in a conventional manner. The frame 15also includes an adapter ring 16 and a ram housing 18 secured to theframe by cap screws 19.

The flywheel drive shaft 14 is provided with gear teeth 20 which meshwith a primary drive gear 21. In this regard, the designation primaryand secondary and upper and lower will frequently be usedinterchangeably in the specification. Most punch presses operate withthe punch moving in a vertical plane and passing through the workpiecefrom above. It should be understood, however, that the unitized drive ofthis invention is equally suitable for punching operations from belowthe workpiece and in some cases punching operations in the horizontalplane. The primary drive gear is keyed to a hollow primary drive shaft22. Primary thrust bearings 24 between the frame and the primary drivegear allow suitable rotational movement of the primary drive gear butpreclude upward movement thereof. The primary drive gear 21 is providedwith an annular track 26 in its lower surface. Positioned for rollingmovement in the track are a plurality of primary thrust balls 28, in thepreferred embodiment three in number, although a minimum of two and morethan three may also be used. The thrust balls also roll in a track 30ina primary wave thrust ring 32. The thrust ring 32 is mounted for linearreciprocation on a plurality of pins 34 (FIG. 7) which are slidablyreceived in a plurality of bores in the primary thrust ring 32.

The track 30 is provided with a plurality of equidistantly spaced camwaves 36, each having a forward inclined slope 36f(FlG. 8) and arearward inclined slope 36r. The top of the cam may be provided with adwell surface of zero slope, such as at 36d. The balls are held inequidistantly spaced positions between the primary drive gear 21 and theprimary thrust ring 32 by a primary thrust ball cage 38. As is readilyapparent, when the balls 28 are in engagement with both the track 26 andthe track 30, rotation of the primary drive gear 21 will cause the ballsto begin rolling. The rate of revolutions of the balls about the axisofthe shaft 22 will be one half the RPM of the primary drive gear. As theballs begin to move up the forward slopes 36f of the cam waves 36, theprimary thrust ring 32 is moved downwardly. Once the balls 28 havepassed over the high spot of the waves and are going down the rearwardslope 36r, the primary thrust ring may be returned upwardly.

It should be apparent that the rate of downward movement of a punchingstroke is determined by the inclination of the forward slope or surface36f of the cam wave 36. This has tremendous significance in controllingthe punching force delivered to the punch at any location along thedownward stroke of the punch. For example, the inclination of theforward surface 36f is very gentle, thus maximizing the punching forcethroughout the entire downward stroke of the punch. Obviously theforward slope 36f could be of a steeper inclinantion to increase thepunch speed, but with less force. If desired, the forward surface 36fcould even be modified to provide a rapid downward movement by a steepinclination, then followed by a gentle inclination for maximum force asthe punch enters the workpiece and followed by a flattened area on thesurface 36d to provide a dwell. The inclination of the rear surface 36ris steep to return the ram quickly to its uppermost position. Obviously,the variations in the force versus stroke speed relationship may bevaried infinitely as desired merely by modifying the shape of the camwaves 36. It should also be apparent that the use of balls roll ing onsmooth surfaces decreases the noise of the machine and eliminates rapidacceleration and decelerations which place undesirable loading on amachine and increase wear. This conversion of rotational movement tolinear reciprocation by the use of the primary wave thrust ring, thrustballs and primary drive gear is an optimum arrangement for transferringrotational movement to linear reciprocation. Another advantage is thatthe inherent reduction of speed between the rpm of the balls and that ofthe primary drive gear 21 allows the use of a high speed lower massflywheel, less expensive to manufacture and maintain than conventionalflywheels.

As is readily apparent, substitution of the primary thrust ring with onehaving more or less cam waves provides a constant variation of thestroke frequency. Further variations of stroke frequency can also beobtained by varying the speed of the power source in a conventionalmanner.

The primary thrust ring 32 is coupled to the punch by a clutch mechanism40 and a ram mechanism 42. The clutch mechanism will be described inmore detail hereinbelow and briefly includes a clutch ring 43 having aplurality of radially directed internal dogs 44 and secondary ornibbling clutch plate 46 having a plurality of radially directedexternal dogs 47. The ram mechanism 42 includes a ram guide sleeve 50keyed for reciprocation in the ram housing 18 and having a lowerinternal shoulder 52 in engagement with a secondary or nibbling wavethrust ring 54. Secured to the bottom of the nibbling wave thrust ringis a ram plate 56. The punch Pn is secured to the ram plate 56 in aconventional manner. Keyed to the primary drive shaft 22 forreciprocation therealong is a nibbling collar 58. Radial bearings 59separate the nibbling drive collar 58 from the primary wave thrust ring32 and the nibbling clutch plate 46 to allow rotation of the nibblingdrive collar relative to the thrust ring and clutch plate. Bolts 34secure the sleeve 50 to the ring 22.

In FIGS. 10B and 10C the drive unit is set in a standard position." Asis readily apparent, downward movement of the punch due to the downwardmovement of the primary thrust ring 32 is accomplished, as shown by thearrows in FIGS. 10B and 10C, by transferring the movement through thenibbling clutch plate 46, thence through the ram guide sleeve 50,through the nibbling wave thrust ring 54, the ram plate 56 to the punch.

Return of the ram to its upper position is accomplished in the preferredembodiment by a primary ram return spring 57. The return spring isconnected at its lower end to a bracket 60 threaded into a bore in thenibbling wave thrust ring 54. At its upper end the spring 57 is coupledto an adjustable bolt 62 which abuts against a spring retainer cap 64.As is apparent, adjustment of the nuts on the bolt 62 will determine thetension of the spring 58 and thus the return biasing force applied toretract the punch from the workpiece. The return spring also maintainsan upward force on the primary thrust ring 32 through the nibbling wavethrust ring 54, the ram guide sleeve 50, and the nibbling clutch plate46 to maintain friction contact between the balls 28, the primary drivegear 21 and primary wave thrust ring 32. The existence of such biasingforce is necessary, of cource, to assure sufficient rolling friction toroll the thrust balls 28 over the cam waves 36.

Upward movemnet of the primary thrust ring 32 is decelerated to reduceimpact. For this purpose, the primary thrust ring is provided with ashoulder 68 (FIG. 4) which confronts an opposite shoulder 69 on theadapter ring 16. As the primary thrust ring moves upwardly relative tothe adapter ring 16, the shoulder 68 as it approaches the shoulder 69traps air therebetween, thus cushioning the upward movement of theprimary thrust ring. The air eventually leaks out in a gap between thesurfaces of the adapter ring and the primary thrust rings as at a. Thecavity between the two shoulders 68 and 69 will be defined as adampening cavity. The cavity is initially vented when the thrust ring isin its lowermost position through dampening cavity ports 70 (FIG. 1) toallow free movement of air into and out of the dampening cavity in allbut the uppermost position of the primary thrust ring.

As thus far described, the ram is capable of reciprocating at the rateof speed determined by the number of balls and the corresponding numberof cam waves. The reciprocation of the ram can be halted by use of theclutch mechanism 40. Although not necessary for a punching operation, afurther desirable feature of the preferred form of the invention is thatthe unitary drive also embodies a nibbling or secondary punch operationwith selection between the standard punch position, nibbling punchposition or neutral position. It should be understood, however, that theunitque rolling-ball motion conversion feature of this invention hasutility in punch presses having only a single speed operation as will befurther described.

In the preferred form of the invention the punch Pn has a workpiece stopand a cutting edge for nibbling operations. As is well known, thenibbling punch is placed in a previously punched hole in the workpiece.Next the work is fed past the punchat a fast rate of speed and the punchreciprocated at a rapid rate, such as 600 hits per minute, allowing thenibbling edge of the punch to cut through the workpiece as it isadvanced post the punch. Of course, in the device illustrated a secondspeed for the punching operation can be provided regardless of whetheror not it is for nibbling. That is if desired a standard punch can beemployed in the secondary speed position as in FIG. 4 since it may bedesirable even in standard punching operations to have the choicebetween a first speed obtained by the standard punch operation and aslightly increased speed in a secondary punching operation.

Nibbling or the second speed is obtained in the preferred embodimentthrough the nibblind drive collar 58 and the nibbling wave thrust ring54. The nibbling drive collar 58 has a secondary thrust ball track 76. Aplurality of nibbling or secondary thrust balls 78 are adapted to ridein the track. The nibbling wave thrust ring 54 is provided with aseondary or nibbling cam track 80 having a plurality of secondary ornibbling cam waves 86. As in the primary cam wave 36, each cam wave 86is provided with a slope inclination to provide a desired stroke ratefor the punch. For a nibbling operation nine waves are provided toincrease the reciprocation of the punch 600 hits per minute with a 6millimeter stroke, for example. This is compared to the example of 200hits per minute with a 30-ton punching force and a stroke of 20millimeters for the primary punching operation.

A secondary or nibbling declutch compression spring 90 lifts the drivecollar 58 off the balls 78 during the standard punch position andneutral position as shown in FIGS. 1 and 3, respectively. The spring isjournaled by a nibbling declutch spring thrust bearing 91. The declutchspring has a spring force of approximately 100 lbs. as opposed to theprimary ram retaining spring 58 which has a spring force of between 200and 300 lbs. In the standard and neutral punch positions the shoulcler52 ofthe ram guide sleeve abuts the nibbling wave thrust ring 54. Whenthe nibbling wave thrust ring 54 is lowered relative to this shoulder asin FIG. 4, the tension of the primary ram return spring 57 overcomes theforce of the declutch spring 90, allowing the nibbling wave thrust ringto move toward the nibbling drive collar to roll the nibbling thrustballs 78. A secondary or nibbling thrust ball cage 92 is provided tomaintain the thrust balls 78 in equidistantly spaced positions. In thenibbling position shown in FIG. 4 the nibbling wave thrust ring is moveddownwardly as the balls 78 ride over the cam waves 86. Reaction forcesagainst the drive collar 58 are transferred to the frame 15 via aplurality of nibbling thrust bearings 94, nibbling clutch plate 46external dogs 47, internal dogs 44, the rotatable primary clutch ring43, and the frame adapter ring 16.

The clutching mechanism 40 will now be described. As best shown in FIG.7, the internal dogs 44 on the rotatable clutch ring 43 slide withinslots 100 in the primary wave thrust ring 21. The internal dogs 44 alsofit within notches 102 in the ram guide sleeve 50. The notches 102 havethree notched steps identified as ST for standard, NE for neutral and NIfor nibbling. The external dogs 47 on the nibbling clutch plate 46 alsoextend into the notches 102. As will be understood, the height of thestep NE is a slight distance, in the preferred embodiment l millimeter,greater than the height of the step ST in the ram guide sleeve.

In the neutral position shown in FIG. 3, the clutch ring 43 is moved tothe centermost position in the notch 102, such that the internal dog 44rests on the step NE. Since the ring 43 abuts the adapter ring 16 andthus can not be moved upward, the guide sleeve is held downapproximately 1 millimeter, the height of the step NE about the step ST.In this position the external dog 47 abuts the step NI and the primarywave thrust ring 32 rests on the nibbling clutch plate 46. However, thel millimeter downward movement of the guide sleeve precludes the primarywave thrust ring from moving fully upward to push the primary thrustballs 28 against the primary drive gear 21. In this position the primarydrive gear continues to rotate but passes over the thrust balls 28 andthus cannot roll them to provide the downward movement of the primarywave thrust ring. Furthermore, the shoulder 52 of the rma guide sleeve50 remains in engagement with the nibbling wave thrust ring 54 topreclude it from being raised any further. The nibbling declutch spring90 meanwhile holds the nibbling drive collar 58 off the secondary thrustballs 78 so that no downward movement is experienced by the nibblingwave thrust ring 54. In this neutral position rotation of the primarydrive gear may continue without reciprocation of the punch.

Since the thrust balls 28 and 78 may be rotating at the time the clutchmechanism is placed into the neutral position, it is desirable to bringthe balls to rest as quickly as possible and preferably before theyagain rise onto the tops of the cam waves. This is accomplished with theprimary thrust ball cage by a plurality of spring brakes 110equidistantly spaced around the frame 15. A small set screw 112 isthreaded into a bore in the frame so that the radially inward positionof the spring brake may be set by adjusting the inward location of theset screws 112. The spring brakes remain in light contact engagementwith the thrust ball cage 38 such that when the driving force isremoved, by allowing the primary wave thrust-ring to drop, the springbrakes 110 quickly bring the thrust ball cage to rest. In practice thisdistance should be less than the distance to the next successive forwardincline of the next cam wave 36. In like manner a plurality of springbrakes 114 (FIG. 7) and corresponding set screws 116 are provided in theram guide sleeve 50 at threee equidistantly spaced positions. Thesespring brakes engage the nibbling bearing cage 92 to bring it to restwhen the balls 78 are de-energized.

In the standard punch position as shown in FIG. 1, the nibbling thrustballs 78 must be de-energized while the primary thrust balls 28 arerolled. To accomplish this the clutch ring 43 is moved counterclockwiseas viewed in FIG. 9 so that the internal dogs 44 rest on the step ST. Inthis position the ram guide sleeve is permitted to rise, pushing thethrust balls 28 into engagement with the rotating primary drive gear 21to begin rolling the balls 28 over the cam waves 36. Thus, in thisposition reciprocation of the punch is obtained in the standardoperating mode. As best shown also in FIG. 1, the nibbling wave thrustring remains held by the shoulder 52 of the ram guide sleeve 50 to allowthe nibbling drive collar to continue rotating without engaging thesecondary thrust balls 78. In the standard punch position the downwardthrust load and reaction load is transferred from frame 15, throughprimary thrust bearings 24, primary drive gear 21, thrust balls 28,primary wave thrust ring 32, nibbling clutch plate 46, external dogs 47,ram guide sleeve 50, shoulder 52, nibbling wave thrust ring 54, ramplate 56 and thence to the punch.

Finally in the nibbling position best shown in FIG. 4 the rotatableclutch ring 43 is rotated to its most clockwise position. In order torotate the clutch ring 43 to this position the ram guide sleeve 50 mustbe moved downwardly by movement of the primary thrust balls 28 to theuppermost surfaces of the cam waves 36. In this position the nibblingclutch plate 46 ismoved downwardly below the level of the rotatableclutch ring 43 so that the internal dogs 44 may be moved directly abovethe external dogs 47. In this position the combined height of theinternal dogs 44 and the external dogs 47 is sufficient to allow theprimary wave thrust ring to drop as in the neutral position shown inFIG. 3 resulting in lowering the primary thrust balls 28 from theprimary drive gear 21 and thus de-energizing the thrust balls. Theheight of the nibbling clutch plate, however, is greater than that ofits external dogs 47 so that the under side of the nibbling clutch plateengages the nibbling thrust bearings 94 and pushes the nibbling drivecollar 58 downwardly to overcome the springs and allows the returnspring 58 to pull the nibbling wave thrust ring 54 upwardly moving thesecondary thrust balls 78 into engagement with the rotating nibblingdrive collar 58. This starts the rolling action of the nibbling thrustballs 78 to begin the higher speed or second speed reciprocatingoperation of the punch P. In the nibbling position the thrust andreaction forces are transmitted from the frame 15 by adapter ring 16,clutch ring 43, thrust bearings 94, drive collar 58, balls 78, nibblingwave thrust ring'54, ram plate 56 and thence to the punch P.

Rotation of the rotatable clutch ring 43 is accomplished from a remotelocation by an actuator mechanism 115. For this purpose, a short rod 116is secured to the clutch ring. The rod 116 has a universal coupler 117attached to its outer end. The coupler is mounted ina centerspring-biased core 118 of a three-position pneumatic valve. The valve isof basically conventional structure, having right-hand cylinder andpiston 120 and a left-hand cylinder and piston 122. Air into theright-hand cylinder moves a core 118 to the left against the resistanceof a spring 123 to move the rotatable clutch ring into the nibblingposition. Venting the cylinder on the right and pressurizing thecylinder 122 on the left moves the clutch ring to the right into thestandard position. Venting both of the cylinders 120 and 122 allows thespring 123 and 124 to return the core to the center neutral position.These respective positions are shown in FIGS. 6A-6C. As best shown alsoin these figures, the tops of the external dogs. 47 have a tapercorresponding to an opposite taper on the bottoms of the internal dogs44. Likewise the steps NE and ST are tapered to allow even engagementwith the internal dogs 44. The taper allows engagement of the internaldogs 46 over the external dogs 47 even where timing is off slightly.These surfaces may be provided with some low friction material such as aTeflon" to allow the actuating mechanism to move the clutch ring intoits desired position once it has started into that position.

It should be understood that the embodiment of the invention shown inFIGS. 1-9 can be used solely for one-speed operation, for two-speedoperation, and particularly for two-speed operation in which the secondspeed is a nibbling operation. FIGS. 1, 3 and 4 and FIGS. 6A-6Cillustrate the preferred technique for placing the drive into nibblingoperation. Assuming a hole is first punched in the workpiece, as forexample by using a standard punch in the punch press and operating thedrive in the standard punch position, the nibbling punch Pn is thensubstituted for the standard punch and the drive operated in thefollowing sequence: Starting from the neutral position (FIGS. 3 and 6A)the clutch ring 43 is rotated into the standard punch position (FIGS. 1and 6B). The thrust balls 28 are engaged lowering the ram guide sleeve50. As the ram guide sleeve begins to return the clutch ring 43 isrotated over the nibbling clutch plate 46 (FIGS. 4 and 6C) pushing itdown to overcome springs 90 thus initiating the nibbling operation.Return of the clutch ring 43 to the neutral position will terminate thenibbling operation. Thus the steps are neutral to standard to nibbling.For one-speed operation the sequence could by neutral to standard toneutral for one stroke or neutral to standard for multiple strokes.

The sequences for standard punch operation are also shown schematicallyin FIGS. lA-10C with the arrow Fs illustrating the'path of the ram forcefrom the fixed frame through the various components. Dimensions L1 andL2 represent the bottom and top of the cam wave of the primary wavethrust ring 32. In FIGS. D and 10E the nibbling or second speedoperation is illustrated schematically with the arrow for indicating thepath of the ram force. Dimensions xl and x2 represent the bottom and topof the cam wave of the nibbling wave thrust ring 54.

For clarity FIG. 11 illustrates a typical ram drive for single speedoperation. In this embodiment the components may be simplified, asshown, and consist basically of the frame 15, primary drive gear 21,thrust balls 28 etc. The clutch ring 43 is basically identical with thepreviously described embodiments, however, since no nibbling operationwould be used the nibbling clutch plate 46 is eliminated. In theembodiment of FIG. 11 the ram plate 56 is coupled to a unitary housing258 which is engaged directly by the primary thrust ring 32.

2. The unitized drive of claim 1, including secondary thrust meanshaving a secondary upper surface provided with a plurality of upwardlyprojecting equidistantly spaced secondary cam waves, at least twosecondary thrust balls positioned on said secondary upper surface,secondary means for rolling said secondary thrust balls over saidsecondary upper surface and for preventing upward movement of saidsecondary thrust balls whereby said secondary wave thrust means is moveddowwardly each time the secondary balls pass over the secondary camwaves, secondary biasing means for urging said secondary ball rollingmeans away from said secondary thrust means, said clutch means includingmeans for disengaging said primary thrust balls-and for overcoming saidsecondary biasing means when said clutch means is in a secondaryposition to engage said secondary ball rolling means with said secondarythrust balls to move said secondary thrust means downwardly each timethe secondary balls pass over a cam wave, and said secondary thrustmeans being coupled to said ram whereby the punch is The housingincludes a slot 202 having a neutral step NE and a lower standard punchposition step ST. The

internal dog on the clutch ring 43 is shown abutting thestep ST so thatthe balls 28 are engaged. As described earlier, rotation of theclutch-ring to engage the step NE holds the unitary housing downwardlyreleasing the balls 28 to stop further punching.

While the preferred form of the invention has been illustrated anddescribed, it should be understood that it is capable of being modifiedby one skilled in the art without departing from the principles thereof.Accordingly, the description is not to be limited to the preferred formillustrated, but is to be limited only by a literal interpretation ofthe-claims appended hereto.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows: 1. A unitized drive for apunch press comprising a rigid frame, primary wave thrust means mountedon said frame for linear movement and having an upper surface providedwith upwardly projecting equidistantly spaced primary cam waves, atleast two primary thrust balls positioned on said primary wave thrustmeans upper surface, primary means for rolling said thrust balls oversaid upper surface and for preventing upward movement of said thrustballs whereby said primary wave thrust means is moved downwardly eachtime the balls pass over the cam waves, ram means coupled to saidprimary biasing means for urging said ram means and primary wave thrustmeans upwardly, clutch means for disengaging said primary thrust ballsfrom said primary ball rolling means when said clutch is in aneutralposition and for engaging said primary thrust balls with saidprimary ball rolling means when in a standard position, and a punch forpunching a hole in a workpiece with each downward stroke of said rammeans. 1

moved downwardly with said secondary thrust means when said clutch meansis in said secondary position for cutting the workpiece.

3. The unitized drive of claim 2, said secondary wave thrust meanshaving substantially more wave cams than said primary wave thrust meansfor increasing the frequency of reciprocation of said secondary wavemeans to perform a nibbling action. I

4. The unitized drive of claim 1 including dampening cavity meanscommunicating with said primary thrust means for entrapping air andreleasing it slowly as said primary thrust means moves upwardly tocushion the impact of the returning primary thrust means.

5. The unitized drive of claim 2, said ram means including a ram guidesleeve having a plurality of guide notches and a secondary clutch plate,said primary wave thrust means having a plurality of slots, said clutchmeans including a rotatable clutch ring having a plurality of radiallyinwardly extending internal dogs movable within the limits of saidslots, when in a neutral position said internal do'gs engageable with aguide notch of said ram guide sleeve and said clutch ring engageablewith the underside of said frame 'means to limit upward movement of saidram guide sleeve.

6. The unitized drive of claim 5, said clutch means including asecondary clutch plate having radially outwardly extending external dogsthat when in the secondary position are engageable with another of saidnotches in said ram guide sleeve and with the underside of said internaldogs of said clutch ring when the clutch ring top surface is engagedwith said frame means to inactivate said primary thrust balls andactivate said secondary thrust balls by allowing said force of saidsecondary biasing means to be overcome.

7. The unitized drive of claim 1, said primary cam waves having ashallow forward incline for providing increased power for punching.

8. The unitized drive of claim 7, saidprimary cam waves having a steeprearward incline. for providing a rapid upward return stroke of said rammeans.

9. A unitized drive for a punch press of the type hav- I ing a rotarypower source, comprising power conversion means coupled to said rotarypower source for converting said rotary power into linear reciprocation,said power conversion means including an upper rotatable member, a lowerrecipro-cable member and a plurality of balls therebetween, means forbiasing said upper and lower members toward one another for engagementwith said balls to roll said balls over said lower member, and means forreciprocating said lower member as said balls are rolled over said lowermem her,

a ram,

means for coupling said ram to said lower member] for reciprocating saidram, and

clutch means limiting the movement of said upper and lower memberstoward one another for terminating said rolling of said balls.

10. The unitized drive of claim 9, said reciprocating means including aplurality of cam waves and wherein the rate of reciprocation can bevaried by varying the shape of said cam waves.

11. The unitized drive of claim 9, said power conversion means includinga nibbling rotatable upper member, a nibbling lower rcciprocable memberand a plurality of nibbling thrust balls therebetween, means for biasingsaid nibbling upper and lower members toward ciprocating means includinga plurality of cam waves.

1. A unitized drive for a punch press comprising a rigid frame, primarywave thrust means mounted on said frame for linear movement and havingan upper surface provided with upwardly projecting equidistantly spacedprimary cam waves, at least two primary thrust balls positioned on saidprimary wave thrust means upper surface, primary means for rolling saidthrust balls over said upper surface and for preventing upward movementof said thrust balls wherebY said primary wave thrust means is moveddownwardly each time the balls pass over the cam waves, ram meanscoupled to said primary biasing means for urging said ram means andprimary wave thrust means upwardly, clutch means for disengaging saidprimary thrust balls from said primary ball rolling means when saidclutch is in a neutral position and for engaging said primary thrustballs with said primary ball rolling means when in a standard position,and a punch for punching a hole in a workpiece with each downward strokeof said ram means.
 2. The unitized drive of claim 1, including secondarythrust means having a secondary upper surface provided with a pluralityof upwardly projecting equidistantly spaced secondary cam waves, atleast two secondary thrust balls positioned on said secondary uppersurface, secondary means for rolling said secondary thrust balls oversaid secondary upper surface and for preventing upward movement of saidsecondary thrust balls whereby said secondary wave thrust means is moveddowwardly each time the secondary balls pass over the secondary camwaves, secondary biasing means for urging said secondary ball rollingmeans away from said secondary thrust means, said clutch means includingmeans for disengaging said primary thrust balls and for overcoming saidsecondary biasing means when said clutch means is in a secondaryposition to engage said secondary ball rolling means with said secondarythrust balls to move said secondary thrust means downwardly each timethe secondary balls pass over a cam wave, and said secondary thrustmeans being coupled to said ram whereby the punch is moved downwardlywith said secondary thrust means when said clutch means is in saidsecondary position for cutting the workpiece.
 3. The unitized drive ofclaim 2, said secondary wave thrust means having substantially more wavecams than said primary wave thrust means for increasing the frequency ofreciprocation of said secondary wave means to perform a nibbling action.4. The unitized drive of claim 1 including dampening cavity meanscommunicating with said primary thrust means for entrapping air andreleasing it slowly as said primary thrust means moves upwardly tocushion the impact of the returning primary thrust means.
 5. Theunitized drive of claim 2, said ram means including a ram guide sleevehaving a plurality of guide notches and a secondary clutch plate, saidprimary wave thrust means having a plurality of slots, said clutch meansincluding a rotatable clutch ring having a plurality of radiallyinwardly extending internal dogs movable within the limits of saidslots, when in a neutral position said internal dogs engageable with aguide notch of said ram guide sleeve and said clutch ring engageablewith the underside of said frame means to limit upward movement of saidram guide sleeve.
 6. The unitized drive of claim 5, said clutch meansincluding a secondary clutch plate having radially outwardly extendingexternal dogs that when in the secondary position are engageable withanother of said notches in said ram guide sleeve and with the undersideof said internal dogs of said clutch ring when the clutch ring topsurface is engaged with said frame means to inactivate said primarythrust balls and activate said secondary thrust balls by allowing saidforce of said secondary biasing means to be overcome.
 7. The unitizeddrive of claim 1, said primary cam waves having a shallow forwardincline for providing increased power for punching.
 8. The unitizeddrive of claim 7, said primary cam waves having a steep rearward inclinefor providing a rapid upward return stroke of said ram means.
 9. Aunitized drive for a punch press of the type having a rotary powersource, comprising power conversion means coupled to said rotary powersource for converting said rotary power into linear reciprocation, saidpower conversion means including an upper rotatable member, a lowerrecipro-cable member and a plurality of balls therebetween, means forbiasing said uppEr and lower members toward one another for engagementwith said balls to roll said balls over said lower member, and means forreciprocating said lower member as said balls are rolled over said lowermember, a ram, means for coupling said ram to said lower member forreciprocating said ram, and clutch means limiting the movement of saidupper and lower members toward one another for terminating said rollingof said balls.
 10. The unitized drive of claim 9, said reciprocatingmeans including a plurality of cam waves and wherein the rate ofreciprocation can be varied by varying the shape of said cam waves. 11.The unitized drive of claim 9, said power conversion means including anibbling rotatable upper member, a nibbling lower reciprocable memberand a plurality of nibbling thrust balls therebetween, means for biasingsaid nibbling upper and lower members toward one another for engagementwith said balls to roll said balls over said nibbling lower member, andmeans for reciprocating said lower member as said balls are rolled oversaid nibbling lower member, said nibbling lower member being coupled tosaid punch, and said clutch means including means limiting the movementof said nibbling upper and lower members toward one another forterminating said rolling of said nibbling thrust balls.
 12. The unitizeddrive of claim 11, said nibbling reciprocating means including aplurality of cam waves.